Barkskin
You touch a willing creature. Until the spell ends, the target's skin assumes a bark-like appearance, and the target has an Armor Class of 17 if its AC is lower than that.
Barkskin 5e 2024 vs. 2014 edition differences
The 2024 version sets the target's AC to 17 if lower, replacing the 16 minimum AC in 2014; it also changes the casting time from an action to a bonus action. The effect description is slightly different but mechanically similar otherwise.